Caring for offspring - certain actions taken by parents to ensure the best conditions for the survival and development of offspring.

Fish with low fecundity show concern for offspring. These fish choose sheltered places for their eggs and protect them from danger. Some carry their eggs with them. For example, the seahorse carries it on the body, and telapia - in the mouth. 

In some fish males take care of the eggs deposited by the female, guarding it, so the male three-needle stickleback builds a spherical nest with two exits from algae, binding them sticky secretion of glands. In this nest, he drives the females, immediately fertilizes the eggs they flushed out and continues to do so until the nest is filled with eggs. After that, he is located above it and, intensely moving pectoral fins, causes water circulation, which contributes to the development of eggs. After hatching young male protects her, rushing to enemies, even much larger than his own size. 

And the female salmon fish cleans the river bottom of silt in the place of future spawning. Then, acting with her tail, arranges an oblong hole in which she swings the eggs in portions as they mature. Fertilized eggs female lateral movements of the body and tail throws sand and gravel, erecting the so-called spawning hillock, on which the current brings more sand. Thus, the eggs and fry in the early stages of spawning are protected by sand from numerous enemies and, in many cases, from freezing.

Caring for offspring in fish is instinctive and continues until the larvae begin to swim freely.